The present invention relates to multifurrow reversible semi-mounted ploughs, comprising a large number of ploughshares, notably more than six and possibly reaching a number of ten or more. In these ploughs, the plough-bodies constituted by two symmetrical mould board ploughshares are fixed to an oblique girder or beam, comprising a central portion oriented substantially along the working axis, with, on either side of this portion, oblique portions extending to the front and to the rear. The plough-bodies are fixed on the oblique portions and the central portion of the beam is rotatably mounted about a longitudinal axis on a support group with one or two wheels of any known type via a lifting device allowing lifting of the whole plough in order to turn it over. This type of plough with eight, ten and even twelve pairs of ploughshares, is increasing in commercial development in proportion to the increased powers of the tractors with a view to providing an increased labour efficiency.
However, the length of these ploughs is large since it reaches 9 meters for eight plough-body ploughs and 11 meters for ten body-ploughs. It follows that land unevennesses result in a difference of ploughing depth of the ploughshares. For an inclination of 5.degree. of the beam between the front plough-bodies and the medial point in line with the support group, the rear plough-body will present, for a plough with ten bodies, a difference of ploughing depth with the front body of 0.087.times.550 cm=48 cm, this difference of ploughing depth being, with an eight body plough and for the same inclination, of 0.087.times.450 cm=39 cm. These values are 9 cm and 16 cm respectively for an angle of only 2.degree.. If in fact the wheel support group passes over a high point or a low point of the ground having a difference of level of x centimeters with the line joining the bearing points of the rear and front bodies and if the ploughing depth of the front body is fixed, for example by the tractor, the ploughing depth of the rear plough-body will be modified by 2x centimeters.
Moreoever, the length of these ploughs increases the width of the landsides at the beginning and at the end of the fields since the ends of the furrows are staggered over the length of the plough and since the coupling necessitates a large evolution surface in order to re-align the plough.